Looking to upgrade my Revel

Hello guys, I need help
I am looking to add disc breaks to my Giant Revel

the front forks need to be changed out, but the rear has the mount holes already, I am thinking abuot just doing the rear for now...I want to convert from the "V" breaks to disc...I need suggestions as to the size of the disc needed and caliper to use

obviously as a sport, I ride at least 30 miles a day, and on weekends around 40-50
I figure I have easily put 55 hundred miles on it already
I have had it almost 11 months and ridden it to hell and back, thr wheels need replacement as they are not really true anymore, I guess I will buy a new bike, looking at the Revel 0 or 1

as a matter of fact just replaced the V break pads on it again today and re adjusted the derailleurs but for the most part this thing had hung in with me for many miles

I hear from many people that my shifers wont last that long...well they have...or that my frame will be falling apart before I hit 3000 miles...well their wrong...and tomorrow I am gonna start doing around 40 on a regular basis...If time permits...lol